This invention relates to a combination wristwatch and calculator and more particularly to a combination solid state wrist calculator and crystal controlled precision timepiece utilizing a common light emitting diode display. The time display and the calculator operations are mutually exclusive and are selected by a mode switch.
This invention constitutes an improvement on commonly assigned and co-pending U.S. patent application Ser. No. 740,409, filed Nov. 1, 1976, and entitled COMBINATION WRISTWATCH AND CALCULATOR and now abandoned. The disclosure of said U.S. patent application Ser. No. 740,409 is expressly incorporated herein in its entirety by reference thereto.
In recent years there have been developed a variety of new wristwatches generally referred to as "Electronic" watches. In many instances these devices use as a timing source a crystal controlled electronic oscillator whose frequency is divided to produce timing signals at a frequency of 1 Hz. and less by a low power solid state divider often incorporating complementary MOS transistors. A wristwatch of this general type incorporating light emitting diodes is disclosed in assignee's U.S. Pat. No. 3,803,827 and others. Through the use of large scale integrated circuits, it is possible to form most of the active components of the wristwatch from a single large scale integrated circuit chip or at the most only a few chips.
Recent years have also seen the development of a new family of electronic calculators generally referred to as pocket calculators. These calculators have taken a wide range of forms, depending upon size and complexity, but in many cases have incorporated integrated circuitry in combination with a digital numerical display. While in some instances the pocket calculators have been sufficiently small to be readily held in the palm of one hand, they have in all instances been quite large and bulky in relation to a modern sized man's wristwatch. One of the limiting factors in further reduction of size of a pocket calculator has been the necessity for a readily accessible keyboard which can be easily and accurately operated without placing undue requirements on the manual dexterity of the operator who performs the desired mathematical calculation.
In order to overcome these and other problems, there is disclosed in assignee's U.S. Pat. No. 3,803,834 a novel wristwatch device which combines the features of both a precision timepiece and a very small or miniature electronic calculator. This is made possible by combining in a novel manner certain features of the newer type wristwatches with certain features of the so-called pocket calculators and by providing an improved and unique miniature keyboard on the watch face.
In the device of that patent, time, which as used herein includes calendar information such as the day, month, and year, is constantly kept. This time information is displayed when desired on the face of the watch in the form of a digital numerical display. The display takes the form of an eight digit electro-optical display using two digits to display minutes, two digits for hours, two digits for the day of the month, and the last two digits for the month of the year.
By manually depressing a mode switch on the wristwatch, the calculator portion of the device is actuated and the eight digit display made responsive to the digital calculator circuitry. By depressing appropriate keys on the face of the wristwatch, the desired mathematical calculations are performed by the calculator circuits within the watch and the result displayed on the same digit display previously used to indicate time. Time is constantly being kept in the wristwatch even when operating in the calculate mode, so that accurate time may be displayed at any instant. In addition, when the device is used to display time, i.e., not in the calculate mode, the calculator circuits are de-energized so as to minimize the power drain on the small sized energy source or battery provided in the wristwatch case.
In assignee's U.S. Pat. No. 3,928,960 there is disclosed an improved device of this type particularly adapted for use with a light emitting diode display. In the disclosure of that patent, the display takes the form of seven display stations, four of which are used to display the same time (and calendar) information as in U.S. Pat. No. 3,803,834. Three of these stations along with the remaining three stations of the display are connected to a calculator circuit to form a six digit numerical calculator display.